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openzeppelin-contracts/scripts/generate/templates/Arrays.js

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const format = require('../format-lines');
const { capitalize } = require('../../helpers');
const { TYPES } = require('./Arrays.opts');
const header = `\
pragma solidity ^0.8.20;
import {SlotDerivation} from "./SlotDerivation.sol";
import {StorageSlot} from "./StorageSlot.sol";
import {Math} from "./math/Math.sol";
/**
* @dev Collection of functions related to array types.
*/
`;
const sort = type => `\
/**
* @dev Sort an array of ${type} (in memory) following the provided comparator function.
*
* This function does the sorting "in place", meaning that it overrides the input. The object is returned for
* convenience, but that returned value can be discarded safely if the caller has a memory pointer to the array.
*
* NOTE: this function's cost is \`O(n · log(n))\` in average and \`O(n²)\` in the worst case, with n the length of the
* array. Using it in view functions that are executed through \`eth_call\` is safe, but one should be very careful
* when executing this as part of a transaction. If the array being sorted is too large, the sort operation may
* consume more gas than is available in a block, leading to potential DoS.
*/
function sort(
${type}[] memory array,
function(${type}, ${type}) pure returns (bool) comp
) internal pure returns (${type}[] memory) {
${
type === 'bytes32'
? '_quickSort(_begin(array), _end(array), comp);'
: 'sort(_castToBytes32Array(array), _castToBytes32Comp(comp));'
}
return array;
}
/**
* @dev Variant of {sort} that sorts an array of ${type} in increasing order.
*/
function sort(${type}[] memory array) internal pure returns (${type}[] memory) {
${type === 'bytes32' ? 'sort(array, _defaultComp);' : 'sort(_castToBytes32Array(array), _defaultComp);'}
return array;
}
`;
const quickSort = `
/**
* @dev Performs a quick sort of a segment of memory. The segment sorted starts at \`begin\` (inclusive), and stops
* at end (exclusive). Sorting follows the \`comp\` comparator.
*
* Invariant: \`begin <= end\`. This is the case when initially called by {sort} and is preserved in subcalls.
*
* IMPORTANT: Memory locations between \`begin\` and \`end\` are not validated/zeroed. This function should
* be used only if the limits are within a memory array.
*/
function _quickSort(uint256 begin, uint256 end, function(bytes32, bytes32) pure returns (bool) comp) private pure {
unchecked {
if (end - begin < 0x40) return;
// Use first element as pivot
bytes32 pivot = _mload(begin);
// Position where the pivot should be at the end of the loop
uint256 pos = begin;
for (uint256 it = begin + 0x20; it < end; it += 0x20) {
if (comp(_mload(it), pivot)) {
// If the value stored at the iterator's position comes before the pivot, we increment the
// position of the pivot and move the value there.
pos += 0x20;
_swap(pos, it);
}
}
_swap(begin, pos); // Swap pivot into place
_quickSort(begin, pos, comp); // Sort the left side of the pivot
_quickSort(pos + 0x20, end, comp); // Sort the right side of the pivot
}
}
/**
* @dev Pointer to the memory location of the first element of \`array\`.
*/
function _begin(bytes32[] memory array) private pure returns (uint256 ptr) {
/// @solidity memory-safe-assembly
assembly {
ptr := add(array, 0x20)
}
}
/**
* @dev Pointer to the memory location of the first memory word (32bytes) after \`array\`. This is the memory word
* that comes just after the last element of the array.
*/
function _end(bytes32[] memory array) private pure returns (uint256 ptr) {
unchecked {
return _begin(array) + array.length * 0x20;
}
}
/**
* @dev Load memory word (as a bytes32) at location \`ptr\`.
*/
function _mload(uint256 ptr) private pure returns (bytes32 value) {
assembly {
value := mload(ptr)
}
}
/**
* @dev Swaps the elements memory location \`ptr1\` and \`ptr2\`.
*/
function _swap(uint256 ptr1, uint256 ptr2) private pure {
assembly {
let value1 := mload(ptr1)
let value2 := mload(ptr2)
mstore(ptr1, value2)
mstore(ptr2, value1)
}
}
`;
const defaultComparator = `
/// @dev Comparator for sorting arrays in increasing order.
function _defaultComp(bytes32 a, bytes32 b) private pure returns (bool) {
return a < b;
}
`;
const castArray = type => `\
/// @dev Helper: low level cast ${type} memory array to uint256 memory array
function _castToBytes32Array(${type}[] memory input) private pure returns (bytes32[] memory output) {
assembly {
output := input
}
}
`;
const castComparator = type => `\
/// @dev Helper: low level cast ${type} comp function to bytes32 comp function
function _castToBytes32Comp(
function(${type}, ${type}) pure returns (bool) input
) private pure returns (function(bytes32, bytes32) pure returns (bool) output) {
assembly {
output := input
}
}
`;
const search = `
/**
* @dev Searches a sorted \`array\` and returns the first index that contains
* a value greater or equal to \`element\`. If no such index exists (i.e. all
* values in the array are strictly less than \`element\`), the array length is
* returned. Time complexity O(log n).
*
* NOTE: The \`array\` is expected to be sorted in ascending order, and to
* contain no repeated elements.
*
* IMPORTANT: Deprecated. This implementation behaves as {lowerBound} but lacks
* support for repeated elements in the array. The {lowerBound} function should
* be used instead.
*/
function findUpperBound(uint256[] storage array, uint256 element) internal view returns (uint256) {
uint256 low = 0;
uint256 high = array.length;
if (high == 0) {
return 0;
}
while (low < high) {
uint256 mid = Math.average(low, high);
// Note that mid will always be strictly less than high (i.e. it will be a valid array index)
// because Math.average rounds towards zero (it does integer division with truncation).
if (unsafeAccess(array, mid).value > element) {
high = mid;
} else {
low = mid + 1;
}
}
// At this point \`low\` is the exclusive upper bound. We will return the inclusive upper bound.
if (low > 0 && unsafeAccess(array, low - 1).value == element) {
return low - 1;
} else {
return low;
}
}
/**
* @dev Searches an \`array\` sorted in ascending order and returns the first
* index that contains a value greater or equal than \`element\`. If no such index
* exists (i.e. all values in the array are strictly less than \`element\`), the array
* length is returned. Time complexity O(log n).
*
* See C++'s https://en.cppreference.com/w/cpp/algorithm/lower_bound[lower_bound].
*/
function lowerBound(uint256[] storage array, uint256 element) internal view returns (uint256) {
uint256 low = 0;
uint256 high = array.length;
if (high == 0) {
return 0;
}
while (low < high) {
uint256 mid = Math.average(low, high);
// Note that mid will always be strictly less than high (i.e. it will be a valid array index)
// because Math.average rounds towards zero (it does integer division with truncation).
if (unsafeAccess(array, mid).value < element) {
// this cannot overflow because mid < high
unchecked {
low = mid + 1;
}
} else {
high = mid;
}
}
return low;
}
/**
* @dev Searches an \`array\` sorted in ascending order and returns the first
* index that contains a value strictly greater than \`element\`. If no such index
* exists (i.e. all values in the array are strictly less than \`element\`), the array
* length is returned. Time complexity O(log n).
*
* See C++'s https://en.cppreference.com/w/cpp/algorithm/upper_bound[upper_bound].
*/
function upperBound(uint256[] storage array, uint256 element) internal view returns (uint256) {
uint256 low = 0;
uint256 high = array.length;
if (high == 0) {
return 0;
}
while (low < high) {
uint256 mid = Math.average(low, high);
// Note that mid will always be strictly less than high (i.e. it will be a valid array index)
// because Math.average rounds towards zero (it does integer division with truncation).
if (unsafeAccess(array, mid).value > element) {
high = mid;
} else {
// this cannot overflow because mid < high
unchecked {
low = mid + 1;
}
}
}
return low;
}
/**
* @dev Same as {lowerBound}, but with an array in memory.
*/
function lowerBoundMemory(uint256[] memory array, uint256 element) internal pure returns (uint256) {
uint256 low = 0;
uint256 high = array.length;
if (high == 0) {
return 0;
}
while (low < high) {
uint256 mid = Math.average(low, high);
// Note that mid will always be strictly less than high (i.e. it will be a valid array index)
// because Math.average rounds towards zero (it does integer division with truncation).
if (unsafeMemoryAccess(array, mid) < element) {
// this cannot overflow because mid < high
unchecked {
low = mid + 1;
}
} else {
high = mid;
}
}
return low;
}
/**
* @dev Same as {upperBound}, but with an array in memory.
*/
function upperBoundMemory(uint256[] memory array, uint256 element) internal pure returns (uint256) {
uint256 low = 0;
uint256 high = array.length;
if (high == 0) {
return 0;
}
while (low < high) {
uint256 mid = Math.average(low, high);
// Note that mid will always be strictly less than high (i.e. it will be a valid array index)
// because Math.average rounds towards zero (it does integer division with truncation).
if (unsafeMemoryAccess(array, mid) > element) {
high = mid;
} else {
// this cannot overflow because mid < high
unchecked {
low = mid + 1;
}
}
}
return low;
}
`;
const unsafeAccessStorage = type => `
/**
* @dev Access an array in an "unsafe" way. Skips solidity "index-out-of-range" check.
*
* WARNING: Only use if you are certain \`pos\` is lower than the array length.
*/
function unsafeAccess(${type}[] storage arr, uint256 pos) internal pure returns (StorageSlot.${capitalize(
type,
)}Slot storage) {
bytes32 slot;
/// @solidity memory-safe-assembly
assembly {
slot := arr.slot
}
return slot.deriveArray().offset(pos).get${capitalize(type)}Slot();
}`;
const unsafeAccessMemory = type => `
/**
* @dev Access an array in an "unsafe" way. Skips solidity "index-out-of-range" check.
*
* WARNING: Only use if you are certain \`pos\` is lower than the array length.
*/
function unsafeMemoryAccess(${type}[] memory arr, uint256 pos) internal pure returns (${type} res) {
assembly {
res := mload(add(add(arr, 0x20), mul(pos, 0x20)))
}
}
`;
const unsafeSetLength = type => `
/**
* @dev Helper to set the length of an dynamic array. Directly writing to \`.length\` is forbidden.
*
* WARNING: this does not clear elements if length is reduced, of initialize elements if length is increased.
*/
function unsafeSetLength(${type}[] storage array, uint256 len) internal {
/// @solidity memory-safe-assembly
assembly {
sstore(array.slot, len)
}
}`;
// GENERATE
module.exports = format(
header.trimEnd(),
'library Arrays {',
'using SlotDerivation for bytes32;',
'using StorageSlot for bytes32;',
// sorting, comparator, helpers and internal
sort('bytes32'),
TYPES.filter(type => type !== 'bytes32').map(sort),
quickSort,
defaultComparator,
TYPES.filter(type => type !== 'bytes32').map(castArray),
TYPES.filter(type => type !== 'bytes32').map(castComparator),
// lookup
search,
// unsafe (direct) storage and memory access
TYPES.map(unsafeAccessStorage),
TYPES.map(unsafeAccessMemory),
TYPES.map(unsafeSetLength),
'}',
);